Minimally invasive image-guided tumour ablation technology is becoming a viable treatment option for a variety of unresectable, or un-dissectionable, tumours, for example. The aim in tumour ablation is the complete kill of the tumour cells. Therefore, the size, shape and location of an ablation zone are evaluated during a planning step before the intervention. For example, WO 2010/0063496 A1 describes a method for planning a tumour ablation procedure. However, tumour targeting ablation planning is often planned freehand and the procedure outcome may vary from operator to operator.